1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, it relates to an image forming processing.
2. Description of the Related Art
Conventionally, in an image forming apparatus provided with toner image forming units for respective colors arranged along an image bearing member for color printing, a distance and a time length from starting of image formation performed by each toner image forming unit to completion of transferring a formed toner image to a recording sheet becomes long. Accordingly, in aim of shortening a printing time, it is controlled to start forming a toner image at a timing earlier than a start timing of feeding a recording sheet from a sheet feeding cassette. In the image forming apparatus which performs such control, when a toner image comes earlier than a recording sheet to a position where the toner image is transferred to the recording sheet, the toner image is disposed of, and then another toner image is formed and transferred to the recording sheet. Accordingly, toner particles are wasted when an arrival of a recording sheet to the toner image transferring position is delayed. In view of this, in an image forming apparatus disclosed in Japanese Unexamined Patent Publication No. 2004-13039, a delay in conveyance of a recording sheet is detected precociously. Then, an image formation performed by an image forming section is suspended immediately when the delay in conveyance is detected, and an arrival of the recording sheet is waited. Accordingly, an untransferred toner image to be discarded is prevented from being generated so that waste of toner particles is eliminated.
In the case of the image forming apparatus disclosed in the above-referenced patent publication, the waste of toner particles can be prevented. However, since the image formation performed by the image forming section is temporarily suspended when a delay in conveyance of the recording sheet is detected, it requires a long period of time to restart the image formation and complete the transfer of a toner image to the recording sheet.